/Engine/Source/Runtime/GeometryFramework/Public/Components/DynamicMeshComponent.h
RenderBuffer Update API. These functions can be used by external code (and internally in some places) to tell the Component that the Mesh data has been modified in some way, and that the RenderBuffers in the RenderProxy need to be updated (or rebuilt entirely). On large meshes a full rebuild is expensive, so there are quite a few variants that can be used to minimize the amount of data updated in different situations. Call this if you update the mesh viaGetMesh(). This will destroy the existing RenderProxy and create a new one.
virtual void NotifyMeshUpdated()